Technical Field
This disclosure relates to video editing, and more specifically, to simulating a virtual lens in a cropped image or video.
Description of the Related Art
It is often desirable to perform crop or zoom operations on high resolution images or video frames to extract a reduced field of view sub-frame. Particularly, for wide angle or spherical images or video, subjects in the originally captured content may appear very small. Furthermore, much of the captured field of view may be of little interest to a given viewer. Thus, cropping or zooming the content can beneficially obtain an image or video with the subject more suitably framed. Wide angle lens used to capture wide angle or spherical content may introduce the perception of distortion that tends to increase near the edges and corners of the captured frames due to the fact that the cameras are projecting content from a spherical world onto a rectangular display. Thus, cropping an image to extract a sub-frame near an edge or corner of a wide angle image capture may result in an image having significantly different distortion than a sub-frame extracted from a center of the image. Furthermore, the cropped image will have a different overall distortion effect than the original image. These distortion variations may be undesirable particularly when combining cropped sub-frames corresponding to different regions of a video (e.g., to track movement of a subject of interest), or combining cropped sub-frames with uncropped frames (e.g., to produce in zoom effect).